#define  _CRT_SECURE_NO_WARNINGS

#include<iostream>

using namespace std;

void test1()
{
	string s1;
	s1.push_back('y');
	s1.push_back('y');
	s1.push_back('h');
	s1.append("hello");
	cout << s1 << endl;
	string s2("world");
	s1.append(s2.begin(), s2.end());
	cout << s1 << endl;
}

int main()
{
	test1();

	return 0;
}